1. Field of the Invention
This invention relates to a process of manufacturing a spacer frame for insulating glass, in which a tubular bar is bent four times in a common plane and the ends of the bent bar are joined to each other.
This invention relates also to an apparatus for manufacturing a spacer frame for insulating glass in that a tubular bar is bent four times in a common plane and the ends of the bent rod are joined to each other, which apparatus comprises a horizontal or inclined backing wall, a holder for holding a tubular bar to be bent, which holder is disposed at one edge of the backing wall, and one or more bending tools, which are disposed at said edge of the backing wall and are operable to bend said bar in a bending plane which coincides with the planar top surface of the backing wall.
2. Description of the Prior Art
A process and apparatus of the kind described hereinbefore have been disclosed in German Patent Specification No. 32 23 881.
In that apparatus the backing wall consists of a plate, which is inclined 10 to 15 degrees from the horizontal. Two bending tools are provided at the top edge of said plate, and are displaceable along that edge. A holder for the tubular bar to be bent is also provided at that top edge of the plate between the bending tools and comprises a plurality of angled supporting brackets for supporting the tubular bar, and a pair of gripping jaws for holding the tubular bar in position. Each bending tool comprises an abutment for guiding and supporting the tubular bar and a pressure-applying roller, which is operable by a toggle joint to cooperate with the abutment so as to act on the tubular bar and to bend said bar about a bending edge of the abutment. The pressure-applying roller is pivoted on an axis which is at right angles to the plate, which has a planar upper surface which coincides with the bending plane. During the bending operation the laterally bent portions of the tubular bar are sliding on the plate.
The two bending tools are operated at the same time. In a first bending operation the tubular bar is formed with two bends to assume a U shape. In a second bending operation, two additional bends are formed between the first and second bends in the tubular bar to form said bar into a rectangular frame. Between the two dual bending operations the two bending tools are moved toward each other.
When all four corners of the spacer frame have been bent, the free ends of the tubular bar contact each other but have not yet been joined to each other. When the bending operations have been completed, the semifinished spacer frame is lifted out of the bending tools and the holder disposed between the bending tools by a mechanical ejector and slides down on the plate and is then taken up by hand and is closed in that a plug connector is inserted into the two free ends of the bent tubular bar. The spacer frame can then be used for its intended purpose.
The known apparatus has the disadvantage that it permits only the bending operations to be automatically performed whereas the frames must be closed at a location which is outside the bending apparatus and said closing is performed either by hand or in a separate closing apparatus to which the frame is transferred by hand. Another disadvantage resides in the springback which is exhibited by the two end portions of the tubular bar when the latter has been bent and the resulting frame is released from the bending tools. As a result of that springback the end portions of the tubular bar are no longer axially aligned but extend at an angle to each other so that a stress will be maintained in the spacer frame when it has been closed. Besides, the angular misalignment of the end portions of the tubular bar which has been released by the bending tools is entirely undesirable for a desirable automatic closing of the spacer frame.